[TYPO3-english] protect content elements from being edited

[Johannes Heinrichs]

dear typo3 community,
i got the following tiny little problem accomplishing my typo3 site:

i want users being allowed only to change specific content types, only
text w/ image content for instance. but still i want them to be able to
see every content of the page. means, by using the access option of the
page or the content element, it would totally hide when the user logs
in. is there a solution telling the system which content types (or even
which specific elements) should be editable and which not, while anyway
all elements are shown and not hidden?

thanks for reading and helping,
greets,
johannes